Due to increasing popularity and significant technological developments in the field of additive manufacturing, it has become critical to develop an efficient dispensing system for manufacturing medical devices, food, electronics, chemicals, and components. As physicians, manufacturing professionals, and individuals make more common use of 3D printing systems, there will be a need to print many different types of devices and even tissue, using material dispensers which can simply and rapidly be exchanged to allow for printing of diverse materials. An article in New York Times, Jan. 27, 2015 entitled “The Operation Before the Operation”, p. 06, describes a need for anatomical models for medicine and the use of 3D printed models.
The need for making anatomical models and actual body parts by additive manufacturing was realized many years ago. The state of the art in this field was summarized a few years ago in an article entitled “Rapid prototyping techniques for anatomical modeling in medicine” by M. McGurk et al. in Ann. R. Coll. Surg. Engl. 1997; 79; 169-174 wherein 3-D printing of models was described. Models were created by spraying liquid through ink jet printer nozzles on a layer of precursor powder, creates a solid thin slice. The printing process was repeated for each subsequent slice until the object was completed as a “green-state” part that was then fired in a furnace to sinter it. The resulting object was then further treated to make a full density part.
In recent years, the development of software for computer controlled robotic X-Y motion systems used in the semiconductor and optics industries has made 3D printing of large objects easier than in former years. Software programs such as SolidWorks, AutoCad 360, and similar software programs make layered construction of 3D objects a relatively low cost and fast task for 3D printing equipment.
To achieve 3D printing of larger objects, print nozzles are directed in the X-Y plane either by placing the object to be made on an X-Y table wherein motion is provided below the nozzles, or mounting rails above the nozzles for X-Y motion directed from above the nozzles. An example of an X-Y table for motion below the nozzles is shown in U.S. Pat. No. 5,760,500 to T. Kondo et al. wherein linear actuator or stepper motors provide independent motion to a table over the X-Y plane. Highly accurate stepper motors for this purpose are described in U.S. Pat. No. 7,518,270 to R. Badgerow and T. Lin. A 3-D printer with overhead control of nozzles is described in U.S. Pat. No. 5,740,051 to R. Sanders et al.
In either motion situation, the nozzles move in the X-Y plane relative to the printed object and also move up in the Z plane starting from a lower level and proceeding upwardly. A layer or lamella is first printed at a low level and then the next layer up is printed and so on until the model or object is completed. Sometimes two nozzles are used, including a first nozzle to spray or extrude a manufacturing material, such as a polymer, and a second nozzle to spray a support fluid for the manufacturing material, which may be soft or viscous. An example of a support fluid may be an ink jet sprayed, ultra violet light cured resin. When the manufacturing material hardens, the faster drying support fluid is dissolved out.
Use of filaments as a supply of material for additive manufacturing is known. For example, in published application 2015/0037446 the authors describe use of a gear to pull filamentary material into a dispensing head for extrusion in a 3D printer. Such a gear drive is similar to the wire drive system shown in U.S. Pat. No. 5,816,466 where consumable wire for welding is advanced by a gear drive mechanism from a reel and consumed in the welding process.
Currently, many researchers and medical industry professionals are looking to additive manufacturing by 3D printing as the future of custom manufacturing of everything from biological organs to medical devices. Additive manufacturing provides the flexibility to produce diverse items very rapidly and at much lower cost than many previous manufacturing methodologies. In particular, additive manufacturing of articles by 3D printing techniques is seen for using patient-specific and patient-derived tissue and bone and for using synthetic tissue and stem cells. One of the problems evident in additive manufacturing is incidental contamination of the manufactured object by dust, airborne particles and moisture. A variable volume sterile environment for additive manufacturing by the present inventor is disclosed in Publication No. 2015/0217514, published Aug. 6, 2015. An object of the invention was to develop a dispensing system for thermoplastic and biological materials compatible for 3D printing equipment that could be used for biological object or device manufacturing by being free of dust, airborne particles and moisture.